<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
</head>
<body>
	
</body>
</html>
<script src='jquery源码分析.js'></script>
<script>
var obj = '';
	alert($.isEmptyObject(obj));//'',null,undefined, [],{}都返回一个true
</script>

<script>
	function Aaa(){};
	Aaa.prototype.constructor = Aaa;//这是弹不出来的，因为在js当中已经打上不被forin的烙印
	Aaa.prototype.show = function(){};//可以弹出来的
	for(var attr in Aaa.prototype){
		alert(attr);
	}
</script>